Process of improving alloys.



UNITED STATES PATENT oEEIoE.

ALFRED WILM, OF SCHLACHTENSEE, NEAR IBRLIN, GERMANY.

PROCESS 0F IMPROVING ALLOYS.

No Drawing. v

To 'all whom t may concern Be it known that I, ALFRED W'ILM, a subject of the German Emperor, and residing at Schlachtensee, near Berlin, Germany, have invented a certain new and useful Imprdved Process of Improving Alloys, of which the following is a specification.

My invention relates to a process for improving alloys such for example, as alloys containing aluminum and magnesium".

The object of my invention is to impart to such alloys an increased strength, elasticity and hardness.

It has been customary heretofore to reheat to redness metals or alloys after they have been completely wrought or worked into the desired shape. The purpose of such heating to redness, however, has been to equalize or remove the strains which were produced by the strain-producing operations, such for example, as cold rolling, drawing, pressing and similar operations, to which the material had been subjected in bringing it into the desired form. In such prior methods, it has been usual to keep the temperature of such reheating as low as possible because it was found that such reheating to redness wasaccompaniedtby a loss of strength and hardness. It has also been customary, when it was desired to avoid the loss of strength and hardness due to such heating to redness, to allow the formed material to age,--that is to say, to stand -unused and unsubjected to any eXternal strains which might afect it,-until with lapse of time the internal strains gradually disappeared or at least were materially reduced. In other words, it has been old in the prior art to subject partly or completely manufactured metallic objects to a relatively low temperature, or to store such objects cold for a time.

My process comprisessubjecting an alloy material, comprising aluminum and magnesium, to a relatively high temperature of between about 420o C. and 580 C. and then, after .it has been cooled either'slowly or by chilling, storing said material for some time prior to use.4

I have found that by this 'treatment a spontaneous improvement takesplace in the material. Of course, it is to be understood that after this treatment hasbeen 'vento the material it is not to be subjecte to anyl further heating in the course of manufac- 'VSpecicaton of Letters Patent.

` Patented Jan. 6, 1914.

Application led March 15, 1910. Serial N o. 549,455.

ture, because such subsequent heating if of any appreciable extent would destroy the advantageous result obtained by luy/process. Hence, with articles of such alloy which pass through any stage of manufacture requiring heating in bringing them into the desired form, it is necessary to await the completion of this heating stage of the manufacture beto-re subjecting the object to my improved process.

By my improved process of treatin alloys containing aluminum, and particu arly aluminum-magnesium alloys, the valuable properties of the material, for lexample the imlt of elongation, elasticity, hardness and strength are very materially' increased beyond anything obtainable by mechanical treatment.

If the final shape has not beenl given to the material before subjecting it to my process, it may, for the purpose of obtaining definite 'qualities be submitted to cold treatment, as, for enample, by rolling, dr'awing, pressing and like operations,.which operations will have an effect on the qualities of the im-.

proved material corresponding to that which such operations have on lthe qualities of metals usually subjected to such operations,-

for example, straightening sheets of such metal, athe production of sharp bends and Hanging, cannot well be performed after the storing.

The presence .of magnesium in the alloy is important for obtaining the desired result.

-When the alloyalso contains other metals,

for example, copper, manganese, nickel, titanium and the like, the advantages of my treatment are still further marked by a considerable additional increase in strength.

It has been found that the spontaneous improvement of the material after heating and during the storing, continues with the time of such storing, and this is particularly true in regard to the hardness.

It may be said that experience has shown that the lhardness increases continually through an ininite time interval, but the rate of increase of hardness is more rapid at first than later.

A measurable effect in the improvement has been noticed after only about one and one half hours, and after twenty-four hours storing a very decided improvement is found. In practice, it is advantageous to store for a longer time than twenty-four hours because this results in a nearer approach to uniformity of the material, which, of course, is a considerable advantage. For this reason, in practice, it is well to store the material for about tour days, although of course, a shorter time may be suflicient.

For the purpose of illustrating the characteristic results which are attained by the improved process, it maybe said that by heating to 500o C. and then chilling in water plates made up of 99.5 per cent. aluminum and 0.5.'per cent. magnesium, and then permitting the treated plates to rest for four days, without subjecting them to any fur; ther treatment or any substantial .Working within that period, the hardness and tensile strength were approximately doubled as compared with pure' aluminum.

slightly changing the shape ot' the alloy and thereupon storing the alloy.

3. The process of improving alloys containing aluminum and magnesium, which comprises heating the alloy to a temperature between 420 C. and 580 C., thereafter cooling the alloy and allowing it to stand to permit spontaneous improvement.

In testimony whereof, I'aflix my signature in the presence of two witnesses.

ALFRED VVILM.

lVitnesse/s:

VODEMAR HAUPT, Y HENRY HASPER. 

